1. Field of the Invention
The present invention relates to a method of manufacturing an illumination unit of the general type as disclosed in the German patent application P 34 34 806.9.
2. Description of the Prior Art
Illumination units of the type set forth above have light guide channels located as lines with light beam coupled into their end faces and along which light can be coupled out from light exit regions in the channel wall. The illumination unit forms a component of a scanning device for illuminating and optionally scanning a planar original. In the scanning device, the illumination unit serves the purpose of microline-by-microline illumination of an original, whereby the light reflected from the original is acquired in columns with the assistance of light receiving elements. The illumination of individual microlines can therefore occur uniformly over the length of the respective microline in that light coupled into the end face in microline-associated light guide channels is continuously coupled out along the respective light guide channel, being coupled out from the channel wall thereof onto the microline. However, a progressive, successive light outcoupling along the longitudinal axis of the light guide channels is also possible, for example by way of a sound wave packet migrating along the light guide channel.
The present invention departs from the basis of a method for manufacturing a flat illumination unit.
Such an illumination unit is described in the publication "Elektronik", No. 24, 1984, p. 114. This known illumination unit is designed as an electroluminescence display unit in which individually selectable image points in the form of individually controllable electroluminescene elements are arranged in a display surface 256 lines and 512 columns. A control and driver electronics for selecting the individual image points is also integrated in the known illumination unit. The structural height of the known illumination unit amounts to 0.8 inches (roughly 2 cm).
U.S. Pat. No. 3,238,859, also fully incorporated herein by this reference, discloses an illumination unit as a component of a photocopier device. The known illumination unit contains a flat electroluminescence layer which is situated in a film arrangement between two transparent, electrically conductive film electrodes. By charging the film electrodes with an alternating voltage, the electroluminescence layer is energetically excited so that it lights up uniformly over its area.